Turns out, it's as tough to drop inward into the inner solar system, as it is to head outward. The problem stems from losing ...

Mercury is nobody's favorite ... ocean of molten carbon that floated to its surface and cooled, leaving a carbon-rich mantle in its wake beneath the planet's crust. Using data from NASA'S ...

With the exception of Pluto, planets in our solar system are classified as either terrestrial (Earth-like) or Jovian (Jupiter-like) planets. Terrestrial planets include Mercury, Venus, Earth, and ...

So, even though Mercury is closer to the Sun, Venus is the hottest planet in the solar system. Mars has a hard, rocky surface with lots of iron in the soil which rusts, making the surface and ...

Narrator: As the solar system grew, four rocky planets ... Mercury, Venus, Earth and Mars. They are the closest four planets to the Sun. They are made of rocks and metals. They have a solid ...